Testing electrode



Patented June 28, 1949 TESTIN G ELECTRODE -:Garl J. Schmid, New .York, N. Y., and "William .3] Koch, lMidland Park, N. AL, :assignors 1 to Julius Schmid, 1110., of New York New York, 'N. Y.,1a, corporation ApplicationMaroh'B, 19425,"Serial No. 582,528

6 Glaims. 1 The present inventionlrelates :to testing apparatus, and more particularly :to an improved mandrel for testing thin tubular rubber articles which are openat one end and closed at the other.

Heretofore it has been customary to test prophylactic rubber articles of-tubular shape for defects by placing the same on a :mandrel of substantially cylindrical shape and substantially conforming to the shape and size of the articles, and then subjecting-the -articles'to test media. A serious difiiculty encountered in connection withthe foregoing procedure is that in placing thearticle on a mandrel aquantity of air is entrappedbetween the: surface of themandrel and the article forming-air pocketsbetween the mandrel and the= ar-ti-cle which interfere with the testing of the article. A'common annoyance is that under the foregoing conditions'it .is impossible to make a propertestof theentire-article by automatic electricaltest means be cause of the presence of the airbetween the article and the mandrel.

An object of the present invention is to eliminate the forgoingdilliculties: and objections.

Another object is to 4 provide simple and inexpensive means for-accomplishing the -ioregoing.

Another object is to. provide animproved mandrel having surface formations for renting, evacuation or permitting theescapeoi air entrapped between the mandrel and the article.

A further object residesin the --arrangementof the means for accomplishing the foregoing.

Other andfurther objects of "thepresentinvention will be manifest from the f'ollowing dea scription and the accompanyingdrawing.

In accordance with the invention, the foregoing objects and advantages -may =be accomplished by providing a *mandrel having ribs or grooves on the surface thereof distributed throughout the area of thesurfaee toprovide fluid flow passages forperrnitting the-escapeof entrapped air. These passages need'not be of any particular design or "patternso long as they are effective toconduct theentrapped air to the open end of the article.

Embodiments of theinvention as shown inthe accompanying drawing are for purposes of illustration and are-not intended aslimitations.

'Inthe drawing:

Fig. l is an-elevationalview of a mandrelrwi-th an article thereon, illustrating one embodiment of the 1 invention;

:Fig. .2 is it a sectional yiew ataken along the line 2-2 of' Fig. :1;

Fig. 3 is an elevational view'o'f-aman'drel with an article thereon illustrating another embodiment of the invention;

F Fig. dis: abottom plan view of the mandrel of fFig. 5is an elevational view of a mandrelillustracting another embodiment of the invention; an

Fig. 6 is an elevational viewof a mandrel illusgrating still another embodiment of the inven- 1011.

Referring to the drawing'in detail-wherein like parts are indicated bythesame reference characters, there is shown a mandrel) of the type for testing thintubular or hollow rubber articles 12 shown in section in Figs. '1 and 3 and being open at one end and closed at the other end, such as, for example, prophylactic Such a mandrel has one end attached to a support .end I l which 'is "substantially hemi-spherical in shape. The body of the mandrel is substantially cylindrical and conforms substantially to the natural or normal shape of the articlel2 so that the article lies in close contactwith' the mandrel Without undue stretching of the article to thereby provide the desired'conditions for testing the article.

In Figs. 1 and 2, the'means for attaining the benefits of the present invention ongitudinally extending and circumferenbermaybe-provided. These grooves extendfrom the apex of the hemi-spherical end l4 upwardly along the side walls of the mandrel to a point above the upper end of the article placed on the mandrel.

In this manner, any air entrapped between the mandrel and the article can escape oris vented or evacuated byway oi'the grooves IE to the atmosphere, thereby eliminating airpockets causing improper test conditions.

In Figs. 3 and Qthe foregoingresultsare attained by providing a plurality of ribs or ridges l8 similarly arranged as thegrooves "to provide a space between the article and the mandreladjacent these ribs orridges for permitting theyescape of entrapped air.

In Fig. 5, longitudinal ed, each provided with nected tributaries or in shown arranged in grooves I'B are illustrata series of fluid'iiow contransverse passages. hereherringbone mannerwith ward ends in fiuid flow communication with the outward ends of grooves E i of other groups. The grooves may be arranged in a regular or symmetrical pattern, such as fiveor six grooves 24 in a group or maybe arranged in an irregular pattern, if desired as will be readily appreciated. By'utilizing this embodiment of the invention substantially the entire surface of the mandrel is provided with means for preventing the formation of air pockets.

In carrying out the electrical testing of the article, in the manner, for example, as disclosed in the aforementioned patent, the mandrel con-- stitutes one terminal of an electrical circuit and the liquid or other medium contacting the outer surface of the article constitutes the other ter minal so that in the event of a defect in the article current will pass through the article to com plete the electric circuit to a signal or other device.

It is to be understood that the grooves, recesses, ribs, ridges, etc., which form the means for evacuating air from between the article and the mandrel as shown in each of the figures of the drawing are greatly enlarged. In actual practice these passages are made very minute so as not to interfere with the'electrical test.

From the foregoing description it will be seen that the present invention provides an improved mandrel for testing rubber articles of the class described. lhe entrapped air-removing means may take many different shapes and forms and are adapted to be readily formed on the surface of the mandrel in any suitable manner.

It is to be understood that while we have illustrated and described three forms or embodiments of our invention we do not wish to be limited to those precise forms as various changes and modifications may be made therein without departing from the spirit and scope of our invention,

What we claim is:

1. A mandrel for testing thin tubular rubber articles open atone end and closed at the other and adapted to snugly fit the mandrel Without the entrapment of air between the mandrel and the article, said mandrel comprising an elongated cylindrical body of electrical conductive material having a series of passages in the surface thereof effectively connected for fluid flow communication and distributed over substantially the entire outer surface of said mandrel for perrnitting the escape or evacuation of air from be tween the mandrel and the article as the article is applied to the mandrel.

2. An article of manufacture comprising a mandrel for testing thin tubular rubber articles open at one end and closed at the other and adapted to snugly fit the mandrel without the entrapment of air between the mandrel and the article, said mandrel comprising an elongated cylindrical body of electrical conductive material having one end adapted for mounting and its other end free, said body being of a length greater thanthe length of the article to be tested Where- '4 by the open end of the article will terminate short of said first mentioned end of the mandrel, said body having formations in thesurface thereof providing passageways along the outer surface extending from predetermined points on the sur face of the body to adjacent said first mentioned end thereof whereby to, permit the escape or evacuation of air from between .the body anl the article to the atmosphere as the article is app-lied to the mandrel.

3. An article of manufacture comprising a mandrel for testing thin tubular rubber articles open at one end and closed at the other and adapted to sungly fit the mandrel without the entrapment of air between the mandrel and the arti cle, said mandrel comprising an elongated cylindrical body of electrical conductive material having one end adapted for mounting and its other end free, said body being of a length greater than the length of the article to be tested whereby the open end of the article will terminate short of said first mentioned end of the mandrel, said body having surface indentations therein communication with each other alonc the outer surfaces thereby providing fluid flow passages extending from predetermined points on the surface of the body to adjacent said first mentioned end thereof whereby to permit the escape or evacuation of air from between the body and the article tothe atmosphere as the article is applied to the mandrel.

4. An article of manufacture comprising mandrel for testing thin tubular rubber articles open at one end and closed at'the other and adapted to snugly fit the mandrel without the entrapment of air between the mandrel and the article, said mandrel comprising an elongated cylindrical body of electrical conductive material having one end adapted for mounting and its other end free, said body being of a length greater than the length of the article to be tested by the open end of the article will terminate short of said first mentioned end of the mandrel, body having a groove formation in the surface thereof providing passageways extending from predetermined points on the surface of the body to adjacent said first mentioned end thereof whereby to permit the escape or evacuation of air from between the body and the article to the atmosphere as the article is applied to the drel.

5. In testing apparatus, an elongated substantially cylindrical mandrel body of electrical eonductive material constituting one terminal of an electrical testing circuit, said body being adapted to support a thin hollow member of dielectric material to be tested and to be immersed in a liquid constituting the other terminal of said circuit, said body having surface formations thereon providing communicating passageways extending from predetermined points on the surface of the body along the outer surface to adjacent one end thereof whereby to permit the escape or evacuation of. air from between the mandrel and the article to the atmosphere when the article is applied to the body. a

6. In a testing device, an elongated substantially cylindrical body of electrical conductive material constituting one terminal of an electrical testing circuit, one end of said body being adapted for mounting with its other end free, and being adapted to support a thin hollow member to be tested having a closed end and an open end and being of dielectric material, the body with the member thereon being adapted to be immersed in a liquid constituting the other terminal of said circuit, said body having minute formations in the surface thereof providing communicating passageways extending from predetermined points on the surface of the body along said surface to adjacent said end thereof, whereby to permit the escape or evacuation of air between the mandrel and the article from said predetermined points to the atmosphere at said end of the body when the article is applied to the body.

CARL J. SCHMLID. WILLIAM J. KOCH.

REFERENCES CITED The following references are of record in the file' of this patent: 

